Health effects of amosite mining and milling in South Africa Jill Murray a,b, * , Gill Nelson b a National Institute for Occupational Health, National Health Laboratory Service, PO Box 4788, Johannesburg 2000, South Africa b School of Public Health, University of the Witwatersrand, 7 York Road, Parktown 2193, South Africa Received 24 August 2007 Available online 5 October 2007 Abstract This study focuses on the amosite mining region in South Africa and associated health effects, compared to other mined asbestos fiber types. Historically, dust and fiber levels were high in the amosite mills and mines, and many miners and members of the surrounding communities were exposed to the fibers. Research has shown that amosite produces both benign and malignant disease. Nevertheless, the mesotheliomagenic potential of amosite is several fold lower than crocidolite. The risk of disease associated with amosite exposure is difficult to quantify. Reasons for this include the scarcity of available information, including fiber measurements, and case ascertain- ment, as well as the juxtaposition of the amosite and crocidolite asbestos seams in South Africa. Ó 2007 Elsevier Inc. All rights reserved. Keywords: Amosite; Mesothelioma; Crocidolite; South Africa; Asbestos 1. Introduction South Africa is unique in that all three commercially important types of asbestos occur and have been mined and widely exported from this country. South Africa was the world’s main commercial source of amosite (grunerite), the name of which is derived from ‘‘asbestos mines of South Africa’’. South Africa was at the forefront of the asbestos mining industry. However, there is a lack of research and docu- mentation monitoring asbestos mines and mills. What little information that is in the public domain needs to be inter- preted with knowledge of the background to geography, geology and demographics. The Pneumoconiosis Research Unit (PRU), now the National Institute for Occupational Health (NIOH), in Johannesburg participated in many of the published studies, and also carried out some unpub- lished work. This information has been drawn on for inter- pretation of the available literature. Historically, there were two amphibole asbestos mining areas in South Africa. Cape Crocidolite was mined in the Northern Cape Province asbestos field, which extends for a length of about 540 km (Fig. 1). No amosite was mined in this area. Five hundred kilometers away, in the north eastern part of the country, is the Pietersburg asbestos field (in Limpopo Province), where both Transvaal crocidolite and amosite were mined. This field is around 100 km long and lies along the Olifants River and its tributaries (Web- ster, 1973). There was very little movement of population between these regions, although more senior mine officials were sometimes transferred between the different mines and mining regions. Many small mines and mills operated in the Pietersburg asbestos field, from about 1920, producing Transvaal cro- cidolite and amosite from deposits in which seams of the two amphiboles often overlapped. Crocidolite mining here (which was in the form of addits) however, never reached the production levels of those in the Northern Cape. The deposits were small and scattered, and were considered to be of poorer grade than those in the Northern Cape. The largest and most important mine in the Pietersburg asbestos field was the Penge group of mines (comprising 0273-2300/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.yrtph.2007.09.011 * Corresponding author. Fax: +27 11 712 6450. E-mail address: jill.murray@nioh.nhls.ac.za (J. Murray). www.elsevier.com/locate/yrtph Available online at www.sciencedirect.com Regulatory Toxicology and Pharmacology 52 (2008) S75–S81